MTS has given some really great info and links.
By modern .... she may want an old-fashioned with more modern fabrics? Or perhaps something abstract? Or bargello? or or or .......... the possibilities are endless!!!!
Best to start by asking her to define "modern". And perhaps better still, ask her to provide pictures/patterns for you.
Sure enough, if you make an assumption, you will be wrong!!!
...................... and as already said, it may be "safer" to say, I don't do modern, and let her do it herself! Will she appreciate what you do? or as my SIL would be, it would never be right or good enough for her! :)